Method and apparatus for determining hematocrit
AssigneeHycel, Inc.
InventorsHenry Robert Angel, Bernard Otto Bachenheimer
Life of this patent
Estimating the term…
Abstract
An apparatus and method are provided for measuring hematocrit. A diluted blood sample is passed through a well-known conductivity sensor providing a sensor pulse for each sensed blood cell. Each pulse has a peak amplitude corresponding to the size of a blood cell passing through the sensor. During a first time period initiated by passing of the sensor pulse above a threshold level, the sensor pulse is coupled to peak detecting means, and a signal indicative of the level of the peak is generated and stored. The value of each stored signal is added to an integrator for a fixed period of time. The value stored by the integrator is thus indicative of hematocrit level for a known sample volume.
Claims14
Apparatus for measuring hematocrit comprising:
- peak detection means for connection to a sensor providing sensor pulses in response to blood cells in a sample, the sensor pulses each having a peak amplitude respectively corresponding to the size of a cell in response to which the sensor pulse is produced;
- storage means connected to said peak detecting means for generating and storing a signal having a level indicative of the peak value sensed by said peak detecting means for each pulse;
- accumulation means;
- controlled switching means coupling said storage means to said accumulation means, timing means responsive to said sensor pulses for initiating a first time period in response to each sensor pulse in excess of a threshold level and providing an output for enabling said storage means to respond to the sensor pulse, said timing means further including means for establishing a second time period in response to the completion of each first time period and providing an output for closing said controlled switching means for a fixed time period during said second time period, whereby said accumulation means is incremented by an amount in correspondence with the level of the stored signal in said storage means.
Apparatus according to cliam 4 wherein said means establishing first time period comprises a threshold amplifier coupled to the sensor providing said sensor pulses, a one shot multivibrator connected for triggering by said threshold amplifier, and gating means connected to said threshold amplifier and said one shot multivibrator for providing a timing signal having a duration equal to the longer of the output of said one shot multivibrator or said threshold amplifier.
A method of measuring hematocrit comprising the steps of detecting the peak of each sensor pulse indicating a size of a blood cell in a sample passing through a sensor, establishing a first time period equal to at least the width of a sensor pulse, generating a signal indicative of the height of the sensor pulse within the first time period and storing the signal to provide a stored signal, establishing a second time period in response to the end of said first time period and incrementing accumulation means for a fixed time period by an amount in correspondence with said stored signal.
Dependencies are inferred from the claim text.